CA 15-3

CA 15-3 is a tumor marker primarily used in the monitoring of breast cancer. It is a protein that is shed by the tumor cells into the bloodstream and can be measured through a blood test. The full name of CA 15-3 is Cancer Antigen 15-3.

Function

CA 15-3 is a mucin-like glycoprotein encoded by the MUC1 gene. It is part of a larger family of cancer antigens that are used to monitor the progression of certain types of cancer, particularly breast cancer. Elevated levels of CA 15-3 can indicate the presence of metastatic breast cancer, although it is not specific enough to be used as a diagnostic tool on its own.

Clinical Use

CA 15-3 is primarily used in the following clinical scenarios:

• Monitoring the response to treatment in patients with metastatic breast cancer.
• Detecting recurrence of breast cancer after treatment.
• Occasionally, it may be used in conjunction with other tests to monitor ovarian cancer and other types of cancer.

Interpretation of Results

The normal range for CA 15-3 levels in the blood is typically less than 30 U/mL. Elevated levels can be seen in:

• Breast cancer
• Lung cancer
• Ovarian cancer
• Pancreatic cancer
• Liver disease
• Benign breast conditions

It is important to note that elevated CA 15-3 levels are not specific to cancer and can be seen in non-cancerous conditions as well.

Limitations

While CA 15-3 is a useful marker for monitoring breast cancer, it has several limitations:

• It is not specific to breast cancer and can be elevated in other conditions.
• Not all patients with breast cancer will have elevated CA 15-3 levels.
• It is not useful as a screening tool for early detection of breast cancer.

Related Pages

• Breast cancer
• Tumor marker
• MUC1
• Metastatic cancer
• Ovarian cancer
• Pancreatic cancer
• Liver disease

See Also

• Cancer antigen
• Blood test
• Glycoprotein
• Mucin

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